Transformer packages with controlled magnetostriction

Abstract

Aspects of the present disclosure include galvanically-isolated (voltage-isolated) transformer-based integrated circuit (IC) packages providing cavities or spaces for an included magnetic core to underdo size changes due to magnetostriction without being constrained or substantially constrained, thus, providing for improved magnetic performance. The circuits, ICs and IC packages and modules may include various types of circuits. In some examples, IC packages or modules may include a galvanically-isolated gate driver or other high voltage circuit.

What is claimed is: 
     
         1 . A method of making a transformer package with controlled magnetostriction, the method comprising:
 providing a substrate having first and second surfaces;   forming an aperture in the substrate;   blocking the aperture with a ferromagnetic core including soft ferromagnetic material and having first and second core portions, wherein the second core portion is unconstrained by the substrate;   covering the first core portion and an exposed portion of the first surface of the substrate with a protective material; and   forming a body about the substrate and ferromagnetic core, wherein the body comprises a mold material.   
     
     
         2 . The method of  claim 1 , wherein the aperture comprises first and second apertures in the first surface of the substrate connected by a cavity in the second surface of the substrate. 
     
     
         3 . The method of  claim 2 , further comprising bonding the second core portion to the first core portion. 
     
     
         4 . The method of  claim 1 , wherein the aperture comprises a cavity with a closed shape and surrounding a region of the first surface of the substrate, wherein the first core portion has a shape matching the closed shape of the cavity. 
     
     
         5 . The method of  claim 1 , wherein blocking the aperture with the first core portion comprises covering the aperture with the first core portion, wherein the first core portion has an area greater than that of the aperture. 
     
     
         6 . The method of  claim 1 , further comprising providing the first core portion with a shaped surface configured for reception by a receiving surface of the substrate. 
     
     
         7 . The method of  claim 6 , wherein the shaped surface comprises one or more surfaces oblique to the substrate. 
     
     
         8 . The method of  claim 6 , wherein the shaped surface comprises one or more stepped surfaces. 
     
     
         9 . The method of  claim 1 , wherein the substrate comprises a printed circuit board (PCB). 
     
     
         10 . The method of  claim 1 , wherein the substrate comprises a lead frame. 
     
     
         11 . The method of  claim 1 , wherein the substrate comprises a ceramic substrate. 
     
     
         12 . The method of  claim 1 , wherein the substrate comprises an alumina substrate. 
     
     
         13 . The method of  claim 1 , wherein the substrate comprises a glass substrate. 
     
     
         14 . The method of  claim 1 , wherein the aperture includes an elliptical shape. 
     
     
         15 . The method of  claim 1 , wherein the aperture includes a circular shape. 
     
     
         16 . The method of  claim 1 , wherein the aperture includes a rectangular shape. 
     
     
         17 . The method of  claim 1 , wherein the aperture includes a square-like shape. 
     
     
         18 . The method of  claim 1 , further comprising applying an adhesive between the first surface of the substrate and the first core portion for facilitating sealing of the aperture. 
     
     
         19 . The method of  claim 18 , wherein the adhesive comprises epoxy loaded with soft ferromagnetic material. 
     
     
         20 . The method of  claim 1 , further comprising covering the second core portion and the second surface of the substrate with a protective material. 
     
     
         21 . The method of  claim 1 , further comprising mounting one or more circuit components to the first surface of the substrate. 
     
     
         22 . The method of  claim 21 , wherein the one or more circuit components comprise one or more integrated circuit die. 
     
     
         23 . The method of  claim 1 , wherein the substrate includes a plurality of first coil portions configured to extend about the ferromagnetic core, and further comprising connecting a plurality of second coil portions to the plurality of first coil portions, forming a plurality of coil windings about the ferromagnetic core. 
     
     
         24 . The method of  claim 23 , wherein the plurality of coil windings comprise primary and secondary transformer coils configured for magnetic coupling. 
     
     
         25 . The method of  claim 1 , wherein the substrate comprises first and second transformer coils disposed about the aperture and configured for magnetic coupling. 
     
     
         26 . The method of  claim 1 , wherein the ferromagnetic core comprises ferrite. 
     
     
         27 . A transformer package having controlled magnetostriction, the transformer package comprising:
 a substrate with first and second surfaces, wherein an aperture is disposed in the first surface;   a ferromagnetic core including soft ferromagnetic material and having first and second core portions, wherein the first core portion is configured to block the aperture, and wherein the second core portion is unconstrained by the substrate; and   a body disposed about the substrate and ferromagnetic core, wherein the body comprises a mold compound.   
     
     
         28 . The transformer package of  claim 27 , wherein the aperture comprises first and second apertures in the first surface of the substrate connected by a cavity in the second surface of the substrate. 
     
     
         29 . The transformer package of  claim 28 , wherein the second core portion is affixed to the first core portion. 
     
     
         30 . The transformer package of  claim 29 , further comprising an adhesive disposed between the first core portion and the second core portion. 
     
     
         31 . The transformer package of  claim 30 , wherein the adhesive comprises epoxy loaded with soft ferromagnetic material. 
     
     
         32 . The transformer package of  claim 27 , wherein the second core portion is integral with the first core portion. 
     
     
         33 . The transformer package of  claim 27 , wherein the aperture comprises a cavity with a closed shape and surrounding a region of the first surface of the substrate, wherein the first core portion has a shape matching the closed shape of the cavity. 
     
     
         34 . The transformer package of  claim 27 , wherein the first core portion has an area greater than that of the aperture. 
     
     
         35 . The transformer package of  claim 27 , wherein the first core portion includes a shaped surface configured for reception by a receiving surface of the substrate. 
     
     
         36 . The transformer package of  claim 35 , wherein the shaped surface comprises one or more surfaces oblique to the substrate. 
     
     
         37 . The transformer package of  claim 35 , wherein the shaped surface comprises one or more stepped surfaces. 
     
     
         38 . The transformer package of  claim 27 , wherein the substrate comprises a printed circuit board (PCB). 
     
     
         39 . The transformer package of  claim 27 , wherein the substrate comprises a lead frame. 
     
     
         40 . The transformer package of  claim 27 , wherein the substrate comprises a ceramic substrate. 
     
     
         41 . The transformer package of  claim 27 , wherein the substrate comprises an alumina substrate. 
     
     
         42 . The transformer package of  claim 27 , wherein the substrate comprises a glass substrate. 
     
     
         43 . The transformer package of  claim 27 , wherein the aperture includes an elliptical shape. 
     
     
         44 . The transformer package of  claim 27 , wherein the aperture includes a circular shape. 
     
     
         45 . The transformer package of  claim 27 , wherein the aperture includes a rectangular shape. 
     
     
         46 . The transformer package of  claim 27 , wherein the aperture includes a square-like shape. 
     
     
         47 . The transformer package of  claim 27 , further comprising an adhesive disposed between the first surface of the substrate and the first core portion for facilitating sealing of the aperture. 
     
     
         48 . The transformer package of  claim 27 , further comprising a protective material covering the first core portion and an exposed portion of the first surface of the substrate. 
     
     
         49 . The transformer package of  claim 27 , further comprising a protective material covering the second core portion and the second surface of the substrate. 
     
     
         50 . The transformer package of  claim 27 , further comprising one or more circuit components disposed on the first surface of the substrate. 
     
     
         51 . The transformer package of  claim 50 , wherein the one or more circuit components comprise one or more integrated circuit die. 
     
     
         52 . The transformer package of  claim 27 , further comprising:
 a plurality of first coil portions disposed in the substrate and extending about the ferromagnetic core; and   a plurality of second coil portions connected to the plurality of first coil portions, wherein the plurality of second coil portions extend about the ferromagnetic core, and wherein the plurality of first coil portions and plurality of second coil portions, as connected, form a plurality of continuous coil loops about the ferromagnetic core.   
     
     
         53 . The transformer package of  claim 52 , wherein the plurality of continuous coil loops comprise primary and secondary transformer coils configured for magnetic coupling. 
     
     
         54 . The transformer package of  claim 52 , wherein the plurality of second coil portions comprise wire bonds. 
     
     
         55 . The transformer package of  claim 27 , wherein the substrate comprises first and second transformer coils disposed about the aperture and configured for magnetic coupling. 
     
     
         56 . The transformer package of  claim 27 , wherein the ferromagnetic core comprises ferrite.